1. Field of the Invention
The present invention relates generally to electroplating. More particularly, the present invention relates to microelectronic device fabrication. In particular, the present invention relates to copper electroplating in the fabrication of interconnect structures in semiconductor devices.
2. Description of Related Art
Copper electroplating processes have been used in the semiconductor industry to fill structures such as dual damascene trenches and contact holes. Miniaturization is the process of reducing the size of semiconductor devices, while crowding more devices onto a relatively smaller area of a substrate.
One phenomenon that is observed during semiconductor fabrication electroplating is the formation of defects such as voids in the metallization. As miniaturization continues to progress, the relative size of a void increases. A significant number of voids will result in a detrimentally lowered conductivity of a metallization such as a contact as well as poor electromigration resistance. In some cases, the void or voids may be sufficiently large to cause an open circuit and the device fails. FIG. 1 is a prior art depiction of a semiconductor structure 10 comprising a substrate with a recess 14 therein. A seed layer 16 is located at the bottom and on the sidewalls of recess 14 and a contact 18 fills recess 14. Present are voids 20 in contact 18. The voids 20 are caused by such forces as non-uniform nucleation at seed layer 16 during plating and inadequate nucleation at a pinhole 22, and large grain formation during plating.
One method of plating comprises using a commercially available copper plating bath composition such as ULTRAFILL(trademark) from Shipley Company, of Marlborough Mass. Other commercially available copper plating bath compositions are is VIAFORM(trademark) and CuBATH(copyright) from Enthone-OMI Inc. of West Haven, Conn. However, use of these copper plating baths may result in a detrimental defect-or voids count besides the contact fill capability may be compromised and incomplete filling may be observed in the contacts.
What is needed is an electroplating bath composition and process that overcomes the problems of the prior art. What is also needed is an inventive contact that overcomes the problems of the prior art.